Federal Funds Purchased and Securities Sold Under Agreement to Repurchase - Schedule of Remaining Contractual Maturity in Repurchase Agreements and Collateral Pledged (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	$ 29,300
Total	29,268	$ 30,239
US Treasury & Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	29,268
Overnight & Continuous [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	1,062
Overnight & Continuous [Member] \| US Treasury & Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	1,062
30-90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	3,900
30-90 Days [Member] \| US Treasury & Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	3,900
Greater Than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total	24,306
Greater Than 90 Days [Member] \| US Treasury & Agency Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements, Remaining contractual maturity of the agreements	$ 24,306